Process for the treatment of waste water

Abstract

The invention provides a process for treating waste water from an industrial process for producing propylene oxide, which comprises subjecting the waste water to a catalytic wet oxidation treatment comprising: feeding a stream comprising the waste water to a reactor; subjecting the stream comprising the waste water to an oxidation treatment in the presence of oxygen and a catalyst resulting in a treated stream; sending at least part of the treated stream to a separator wherein the treated stream is separated into a gas stream and a liquid stream; and recycling part of the liquid stream to the reactor.

That which is claimed is: 
     
       1. A process for treating wastewater comprising subjecting the wastewater to a catalytic wet oxidation treatment comprising:
 feeding a stream comprising the wastewater to a reactor, wherein the wastewater is from an industrial process for producing propylene oxide containing hydrocarbons and salts; 
 subjecting the stream comprising the wastewater to an oxidation treatment in the presence of oxygen and a catalyst resulting in a treated stream; 
 sending the treated stream to a separator wherein the treated stream is separated into a gas stream and a liquid stream; and 
 recycling part of the liquid stream to the reactor. 
 
     
     
       2. The process according to  claim 1 , wherein the oxidation treatment step is conducted at a temperature in the range of from 120 to 300° C. and a pressure in the range of from 2 to 20 MPa. 
     
     
       3. The process according to  claim 1 , which is carried out in a continuous manner. 
     
     
       4. The process according to  claim 1 , wherein a gas stream comprising oxygen and optionally an inert gas is fed to the reactor. 
     
     
       5. The process according to  claim 4 , wherein the amount of oxygen in the gas stream comprising oxygen and optionally an inert gas is in the range of from 1 to 100 vol. %. 
     
     
       6. The process according to  claim 4 , wherein the gas stream comprising oxygen and optionally an inert gas is a gas stream consisting of air or a gas stream consisting of a combination of air and an additional amount of one or more inert gases. 
     
     
       7. The process according to  claim 4 , wherein the gas stream comprising oxygen and optionally an inert gas is a gas stream wherein the oxygen concentration is higher than that in air. 
     
     
       8. The process according to  claim 1 , wherein the catalyst is used in an amount (in grams) per the feed rate of the stream comprising the wastewater (in litres per hour) in the range of from 10 to 300 g/(l/h). 
     
     
       9. The process according to  claim 1 , wherein of from 1 to 99 vol % of the liquid stream separated by the separator is recycled to the reactor. 
     
     
       10. The process according to  claim 1 , wherein the catalyst comprises metal nanoparticles-doped porous carbon beads. 
     
     
       11. The process according to  claim 1 , wherein the wastewater before treatment in accordance with the process has a chemical oxygen demand value in the range of 80,000 to 125,000 mg/L.